Always treat rams with respect, and do not make pets of them, as some can become dangerous.
Fig. 289 Rams can injure people, so always take care when you are near them, and don’t turn your back on them.
The Effect of Body Condition
Tupping time is the start of the annual production cycle, and is crucial as it largely determines how many lambs are going to be born about five months later. Management in the weeks before tupping time can have a significant impact on the fertility of rams and the ovulation rate of ewes. Examination of rams to check that they are likely to be fertile has been described in Chapter 3. Sperm take six to seven weeks to mature, so ram care must be considered at least two months in advance, to make sure they are fit, with a condition score of 3.5 to 4 so they can afford to lose weight over the tupping period.
Some supplementary feeding may be necessary – there are specially formulated concentrates for rams, although a ration based on whole barley with added protein such as soya or peas and beans is perfectly acceptable. Mineral content needs to be considered, as diets high in magnesium or unbalanced in calcium and phosphorus can lead to the formation of bladder stones, a potentially fatal condition. This is particularly a risk in animals such as show rams fed concentrates for a prolonged period. It may be best to feed a special ram concentrate to these, as it should be correctly balanced for these minerals.
During tupping, rams will inevitably lose weight if they are with large groups of ewes. Some shepherds train them to come for feed during this time. Rams with small numbers of ewes, such as in pedigree or hobby flocks, probably do not need any supplementary feeding if the grass supply is adequate.
Fig. 290 This group of hill rams is on good grazing in preparation for sale and for the beginning of the tupping season.
Fig. 291 Check over each ram (as described in Chapter 3) to make sure they are likely to be fertile.
Fig. 292 Make sure newly purchased rams, particularly ram lambs, have not been pushed on large amounts of concentrates as they may be fat rather than fit, which may adversely affect their fertility.
For ewes, actual condition score at tupping time is a key factor, although whether the animals are gaining or losing weight has a major influence, with loss of weight having an adverse impact. Flushing ewes on good grass, which results in an improvement in body condition, has long been recognized to have a positive effect on ovulation rate, although ewes that are already in good condition and are maintained at this level will perform equally well. Loss of weight during tupping time and for the first month of pregnancy must be avoided if at all possible, as this will lower ovulation rates and increase embryo deaths.
In the past it has been customary to give ewes a worm drench just before tupping. It is now known that this is not usually necessary, apart possibly for yearling and thin ewes, and as well as being a waste of money, it could help hasten the onset of anthelmintic resistance (Chapter 7).
The Manipulation of Breeding
The breeding season is triggered by the onset of lengthening nights, with the length of each breeding cycle being sixteen to seventeen days. Different breeds vary in the time of year at which the ewes start to come into season and the number of breeding cycles that they will have. At one extreme Dorset Horns and polled Dorsets will breed at most times of the year, whereas primitive breeds such as the Soay will have a brief breeding season of perhaps two cycles late in the year ensuring lambs are born when grass is plentiful. Down breeds such as the Suffolk will breed early in the year (late July and August), whereas commercial ewes such as the Mule will come into season from September onwards with peak fertility in October and November; for hill breeds, November and early December is peak activity time.
Fig. 293 Flushing ewes that are in below optimal body condition on good grass aftermath in the period running up to tupping time will have a positive effect on ovulation rate and therefore on lambing percentage.
Fig. 294 If tupping time is late in the year and grazing is of dubious quality, extra feed can be supplied by giving nuts on the ground.
With most British breeds, if rams are allowed to stay in with ewes throughout the year and the flock is left to its own devices, the ewes will generally lamb over a considerable period of weeks starting with a scatter of early breeders, followed by some bunching, then with a long tail of stragglers. It is very difficult to keep up the level of inspection and care needed over such a long period, and lamb losses will inevitably occur. Some times unexpected things happen, such as experienced by one of the authors, when three sheep that had lambed early in the year lambed again in early autumn!
To avoid long-drawn-out lambing seasons and unexpected events it is best to keep the rams separate for most of the year and to use a method of trying to ensure that tupping, and therefore lambing, takes place over a compact period. In commercial flocks the aim is usually to have about 90 per cent of the flock lambed within a five-week period, meaning that all necessary resources can be available to minimize losses.
There are several methods of advancing or compacting the breeding season. These need to be carried out correctly otherwise it may be an expensive waste of money – your vet should be able to advise on details. The methods are described below, and may be summarized as the ‘ram effect’, the synchronization of oestrus, and melatonin implants.
The ‘Ram Effect’
If ewes are kept out of the sight and smell of rams for three to four weeks just prior to the onset of the breeding season, and the rams are then introduced, the ewes will have a silent heat within two to four days. Ewes will then go on to have a fertile heat in two waves at roughly eighteen and twenty-six days after the introduction of the ram. This effect comes about because of special scents, or ‘pheromones’, which are produced in certain glands, particularly on the head of the rams. These waft about in the air and stimulate hormonal activity in the brains and ovaries of the ewes. This will not work if ewes are already cycling.
Fig. 295 Keeping rams in an adjacent field for about ten days before putting them with the ewes can help tighten the lambing period, but this only works if the rams have been kept well away from the ewes beforehand, the ewes have not started cycling, and the fences are good.
This method often results in a few ewes lambing in the first couple of weeks, followed by most of the rest of the flock lambing over a week to ten days. The early lambers can be avoided by putting the rams in an adjacent field before letting them in with the ewes about ten days later, although you will need good fences for this method to work!
Vasectomized Rams
These rams also work by the ‘ram effect’, but as the vasectomized rams are not fertile, no ewes will get pregnant until fertile rams are introduced; this should be no later than fourteen days after putting in the vasectomized rams. The end result should be an advancement of the breeding season by one to two weeks, and a tightening of the spread of lambing.
Fig. 296 When choosing rams to be vasectomized, do not use old, failed rams. Instead choose young, active ram lambs of a crossbreed or at least a different appearance from fertile rams so that they are easily identified. If they are well cared for they should last six to seven years.
Fig. 297 A vasectomy operation: the vas deferens, the tube which carries sperm from the testis, has been located and a piece will be removed; when both sides have been completed the ram will be rendered infertile.
Fig. 298 The incisions will heal leaving scars, but make sure the vasectomized rams are clearly identifiable to avoid any mix-up with the fertile rams.
Synchronization of Oestrus
The synchronization of oestrus is achieved by using intravaginal progestagen sponges with or without the injection of a hormone, PMSG, at removal – these can be used to advance the breeding season by two to four weeks (in which case an injection of PMSG is needed at sponge withdrawal – take advice on the dose, as too much can result in too many eggs being produced and unwanted multiple births) or to synchronize oestrus within the normal breeding season. Sponges should be inserted into the vagina with care so as not to damage the sheep, using a clean technique by means of the disinfectant or antiseptic cream provided. Sponges are left in situ for fourteen days before removal by pulling on the strings, which should still be visible at the vulva of the ewe.
Fig. 299 If intravaginal sponges are being used, make sure they are carefully disposed of so dogs cannot eat them.
When the sponges are removed it is normal for a little milky, unpleasant-smelling fluid to come away too – this will not affect fertility. Occasionally a sponge cannot be found at removal time. This may be because the sponge has been lost, or because the strings have disappeared into the ewe’s vagina (though this is rare). Careful exploration with a clean finger may find the strings if this is the case, but if not, it may require an examination by your vet to determine what has happened.
Be careful to dispose of used sponges safely – dogs will eat them if they get the chance, and this can be fatal. Ewes will come in season about two days after sponge removal. As all the ewes will come in season in a very short time period, extra rams will be needed, with one ram to ten ewes recommended.
Melatonin Implants
These implants are inserted under the skin at the base of the ear, and work by fooling the sheep into thinking that longer nights have arrived four to six weeks before they actually have done. This stimulates the early onset of ovarian activity, and is particularly useful in increasing the lambing percentage of early lambing flocks. Good advance planning is needed if these are to be used, since the programme begins thirty weeks before the desired date for lambing. It is very important to follow the instructions for use, otherwise it may be a costly experience without any benefit.
Management of Tupping Time
The ram-to-ewe ratio usually recommended is one mature ram to forty or fifty ewes, although some people think one to eighty to 100 ewes is possible, although a greater number of rams is needed if synchronization has been used. Ram lambs may or may not work successfully with a smaller number of ewes, depending on their age and maturity.
Whether one of the above techniques to advance or condense the breeding season is used, or the sheep are left alone and nature is just allowed to take its course, it is extremely useful to be able to monitor whether the rams are actually working and that the ewes are getting in lamb. This way, problems can be picked up early and remedied without too much loss of valuable time. The usual method of doing this is by applying colour (raddle) in the form of a specially prepared paint or a crayon to the brisket of the ram, which leaves a mark on the rump of ewes that have been mated. The colour can be changed about every two weeks, which will then identify the period of mating and any ewe that has been mated more than once. As well as identifying that ewes are coming into season, being mated and getting into lamb, later in the year it allows grouping of ewes by expected lambing date.
For pedigree flocks using just one ram with a group of ewes, use of raddle is particularly crucial as an infertile ram can ruin a whole breeding season. Where groups of rams are used with commercial ewes, raddle use monitors overall flock activity, and the occasional infertile ram will escape detection. Although it is often assumed that using several rams ensures successful pregnancies, in rare cases there can be infectious causes of ram infertility affecting many in the group, so it is always worth using raddles and not leaving things to chance.
At the end of the breeding season rams should be removed so there is a firm date for the expected completion of lambing. The rams should not then be consigned to a distant paddock and forgotten about until the following year: they should be checked over, any past their best culled, lameness and other problems dealt with, and sufficient food given so they regain an acceptable body condition score.
Fig. 300 This ram is fitted with a harness that takes a crayon raddle. These can easily be changed to a different colour.
Fig. 301 Here is one ewe with yellow colour on the rump and another with red. It is best to start with a light colour, then move to darker ones – for example yellow, then red – so the colour can clearly be seen if a ewe is mated again at a later date.
Fig. 302 Here, blue raddle colour has been applied to the ram’s brisket. This will need renewing every few days. This should be a colour specifically prepared for this purpose – ordinary paint or other products should never be used.
Fig. 303 The harness is adjustable for different sizes of ram, and should be checked regularly to make sure it is neither too tight nor too slack.
Fig. 304 If rams are not raddled it is impossible to know what is happening in a flock at tupping time.
Fig. 305 The harness must be fitted so that it sits centrally on the brisket. Change the colour at least every two weeks. In older harnesses the replaceable crayon was fitted by means of a split pin, and the ends of the pin could damage the inside of the ram’s leg if not fully turned down. Modern harnesses do not have this problem.
Fig. 306 This ram is obviously lame at a crucial time of the year, as is a ewe in the background. These animals should be treated promptly. Lameness in a ram at this time can have a major effect on flock performance.
Artificial Insemination (AI) and Embryo Transfer (ET)
These techniques are used much less in sheep than in cattle in the UK, although AI is used extensively in some countries. Both are methods of using animals with superior characteristics to produce more offspring. ET is exclusively confined to high value pedigree sheep and involves a strict programme of hormone use to prepare donors and recipients. Embryo recovery is by laparoscopy.
With AI, fresh semen can be used by introduction into the anterior vagina or entrance to the cervix, with results as good as natural mating. Use of frozen semen in the same way is usually much less successful owing to the long, tortuous nature of the ewe’s cervix, which is a formidable barrier to sperm that have been frozen. Therefore this is usually carried out by laparoscopy, with semen injected straight into the uterine horn.
Both procedures require experienced operators to perform them, with laparoscopic techniques carried out or supervised by a vet.
Fig. 307 A typical fighting injury which has become infected and needs cleaning up.
Specific Problems of Rams
Fighting Injuries
It is common for rams to fight with each other, particularly when newly introduced. In extreme cases, injuries can be fatal – and costly, usually a broken neck. Established groups will spar with each other, but mostly know their place in the pecking order, and head wounds are the most likely outcome. If a new ram is to be put in a group, or even with just one other, serious injury can usually be avoided by confining them to a small pen for a day or two. Here they can establish who is the stronger, but without killing each other. Head wounds can be a problem when flies are around in summer, so spray with antiseptic or antibiotic and apply an SP pour-on to protect them.
Urolithiasis (Bladder Stones)
This is a serious and potentially fatal condition in rams in which small stones, or more commonly sand-like particles, form in the bladder. If these get into the urethra which carries urine to the exterior, they cause an obstruction. If not recognized quickly it can cause irreversible damage, with rupture of the urethra or bladder. The signs of obstruction are abdominal pain, kicking at the abdomen, and crouching to attempt to urinate. If not noticed early on, urine leaks into the lower abdominal wall, and the affected animal becomes dull and will eventually die.
Fig. 308 Show rams are particularly at risk of developing bladder stones if they are fed concentrates throughout the season. Make sure they are fed food that is specifically formulated for rams, and that they are given as much time at grass as possible.
Treatment is difficult and not worth attempting except in early cases; sometimes your vet may be able to snip off the urethral appendage on the end of the penis (see Chapter 3), and if this is the only part obstructed the ram may be able to pass urine again. If this does not work, more complicated surgery is necessary if the ram is valuable enough to warrant it, but may not succeed. Sometimes there has been prior kidney damage, which makes the outlook poor.
The main causes are lack of water; feeding too much concentrate, especially if not formulated specially for rams; and an imbalance of minerals in the diet, especially calcium, phosphorus and magnesium.
Fig. 309 The narrow tube at the end of the penis is most likely to become blocked with stones. Wether lambs can also be affected (see Chapter 13). Females do not develop an obstruction as the urethra is wider, and any small stones are easily flushed out when they urinate.